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Modified on Monday, 02 February 2015 01:12 PM by mpieler Categorized as Extrusion Hints
Vol. 27 #2, November 2000

In coextrusion in a single manifold flat die, the ability to maintain good layer uniformity depends greatly on the design of the die. However, it is also affected by the ratio of the viscosities of the polymers and the ratio of their flow rates. For an A/B or A/B/A structure, the tendency of the cap layer, A to encapsulate the base or core layer, B will be higher when the viscosity of A is low and/or the flow rate of A is high relative to those of polymer B. When either of these ratios differs by more than a factor of ten, a multi-manifold die is usually recommended.

- Wayne A. Gifford, Dieflow

See also:
  • Coextrusion alarms
  • Coextrusion control
  • Coextrusion: melt strength

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